A fireplace generally includes a cavity which is commonly referred to as a firebox and which is defined by masonry walls, a hearth, and a rear wall with the cavity connected through a flue to a chimney. The draught of cold outside air which travels downwardly within the chimney is redirected upwardly by a damper which provides a necked down opening between its free end and a front wall of the chimney. Energy sources such as coal, wood and the like which are supported for burning adjacent the hearth cause the room air to be heated.
Unfortunately, in standard fireplaces, the heated air is drawn upwardly between the free end of the damper and the chimney wall at the flue and flows upwardly and out the chimney. It is well known that while a fireplace is a desirable feature in a home from the standpoint of nostalgia and aesthetic values, it may result in a net outflow or loss of heat from a room rather than increase the temperature thereof. The heat loss occurs because of the relatively large volume of air that must flow into the fireplace to sustain combustion with the products of combustion being exhausted up through the chimney. In the past, the air required for combustion has been drawn from inside the house, with the result that air heated by a central heating system is pulled from the house to sustain a fire that heats radiantly only the area adjacent the fireplace opening.
As a result of today's energy crisis, a number of devices for improving the efficiency of existing fireplaces have appeared in the marketplace. A well known grate supported on legs for holding coal or wood has been replaced in some fireplaces by a device which comprises relatively large circular tubes for heating air and redirecting same back into the room. Various arrangements of fans are used to retrofit existing fireplaces and are integral parts of new installations for redirecting heated air into the room rather than permit it to escape through the flue with no benefit to the occupants of the room. In still other arrangements, such as, for example, an air grille fitted into a raised hearth, exterior air is drawn into the house to feed the combustion.
In the most current prior art, one triangular arrangement of plates which are installed between side walls of an existing fireplace in overlying relation to a heat source serves to deflect heat into a room and to direct residual combustion gases to the fireplace flue as well as to heat the overlying upper panel so that it radiates heat into the room. (See U.S. Pat. No. 3,952,722) Another device which is shown in U.S. Pat. No. 3,802,415 channels the flow of gases in the throat of a chimney without relying on a conventional damper and masonry projection and regulates the draught.
Early on in the prior art, J. Spear in U.S. Pat. No. 280,411 disclosed a damper comprising two pivotable valves which were both oriented horizontally to close off the room to cold outside air and the front one of which was oriented angularly downwardly toward the heat source to reflect heat and light into the room. J. Southward in his U.S. Pat. No. 239,873 accomplished the same result with a plate which was pivotally mounted along a top rear edge of his energy source holder, and T. F. Card in U.S. Pat. No. 27,886 shows a curved plate cantilevered out from a rear wall of the firebox and having its free upper edge supported by tie rods from the rear wall. D. A. Ross, patentee of U.S. Pat. No. 39,836 forms a part of the background art of this invention in that he shows a fireplace equipped with an ogee rotating back which may be swung rearwardly to allow the charging with an energy source after which it is allowed to come to rest in engagement with the front of the fireplace opening.
None of the above-mentioned devices which are the subjects of patents nor those which are presently on the market provide the consumer with a means for expeditiously retrofitting an existing fireplace to cause substantially more of the heat generated to enter the room. Clearly, now more than ever before in this century, there is a need for such a device which may be simply constructed and not require considerable financial investment by the homeowner.